A group of scientists from the U.S. and Canada has assessed five strategies being discussed to combat climate change: reducing CO2 emissions, carbon sequestration by biological means land and ocean CO2 storage in geological repositories and liquefied artificial increase cloud cover of the planet to increase the amount of radiation reflected into space. His conclusion is that the most effective and realistic answer is the first option, the reduction of emissions. Among other strategies, some can help achieve the goal of curbing warming, but others involve problems and uncertainties. ” We have seen that climate engineering does not provide an optimal solution,” says the lead researcher, Daniela Cusack, University of California at Los Angeles (UCLA). ” The perfect option is to reduce emissions. We have to cut the amount of emissions we are putting into the atmosphere if, in the future, we want to have something like Earth today. ” The goal, researchers say, is to reduce the nine gigatons (9.000 million tons) of CO2 that human activities introduced each year into the atmosphere.
Cusack and his colleagues have applied criteria ” technical, economic, ecological, institutional, ethical dimensions and social acceptance” for evaluating five options considered most promising emission containment, explain in the journal Frontiers in Ecology and the Environment.
None of these alternatives is as close to the objective of reducing emissions and increasing energy efficiency and low carbon fuels, the researchers said in a statement from UCLA. The technologies already available, they add, could reduce the amount of carbon added to the atmosphere in about seven gigatons per year.
Among the strategies analyzed, carbon sequestration by biological means, such as plants, is the most promising option among alternative climate engineering. If the trend of destruction of existing forests and plantations while forests increase is reversed, can be set up to 1.3 gigatons of CO2 per year in the form of plants, researchers estimate that recall that deforestation is responsible for a gigaton of emissions into the atmosphere each year.
The researchers also stress the benefits of proper management of agricultural land. It may also help other less known form of biological carbon sequestration: the production and burial of charcoal produced through processes of high temperature and pressure plant debris they generate fewer emissions of CO2 to the atmosphere compared to the normal breakdown. This can work to store the carbon fixed by plants while alive. ” The charcoal has been used for centuries to improve agricultural land, but scientists are now beginning to appreciate its potential to set greenhouse gas,” recalls Cusak.
Another form of biological carbon sequestration, however, is more controversial, the researchers conclude. This is fertilizing the ocean with iron to stimulate the growth of algae that sequester carbon. To Cusak and colleagues this strategy is impractical. It is estimated that less than a quarter of the carbon sequestering algae will sink to the ocean floor for a long period of time, while the rest will become food for other species and eventually the CO2 in the atmosphere, they argue. And not forgetting that algal blooms cause a decrease in oxygen in the water available for other organisms. This strategy has been tested in several ocean experiments and results about its effectiveness as carbon sequestration has proved indeed controversial. It is the least desirable for these scientists who analyzed the option.
The capture and storage of liquefied CO2 in geological formations is being used already associated with extraction plants, petroleum refineries and coal mines (million tonnes of carbon dioxide stored and annually), and advances in technology for other sectors industrial. Researchers estimate that this strategy has the potential to permanently store more than one gigaton of carbon each year. However, Cusack and his colleagues warn that a leak of these stores “could be fatal to humans and animals ” in the environment, so that, although it is unlikely an accident, can not get full social acceptance.
The idea of forming artificial clouds to prevent global warming by increasing the amount of solar radiation reflected back into space, or even installing reflectors in space to achieve the same end, it seems impractical. The researchers point out that cloud seeding is relatively easy, but its potential impact is full of uncertainties in the case of massive use.
The conclusion of the study, the scientists write in Frontiers in Ecology and the Environment, is that although the reduction of emissions of greenhouse gases must be the primary response to climate change, “Some approaches to climate engineering low risk and cash balance cost / effectiveness should be supplementary. “